The invention relates to a liner, particularly to a liner for a pipe, tube or conduit and to a method of lining such a pipe, tube or conduit (hereinafter xe2x80x9cpipexe2x80x9d)
Pipes such as existing water or gas pipes often require repair as they degenerate with age. Carrying out such repairs in situ avoids the expense of excavating the pipe. However, a liner must be pliable enough to be inserted,
For maximum efficiency it must not substantially reduce the effective bore of the pipe and it must maintain its integrity in the presence of defects, joint gaps and other surface irregularities likely to be encountered inside a pipe in need of repair, It is also essential that fluid is not allowed to enter any annular gap between the liner and its host pipe, so that it is normally necessary to make special provision for sealing this gap wherever the liner is terminated or punctured to allow fluid to pass out of the pipe.
It is an object of the invention to seek to provide a liner and process for installing same which can meet these criteria, without the need for special provision for sealing the annular gap.
According to a first aspect of the invention there is provided a liner for a pipe, comprising a flexible material which is formable into a tube, a major surface of which material has means adapted to increase the surface area thereof.
The means may comprise an elastomeric property of the flexible material.
The means may comprise a profile applied to the material. This is a relatively simple way to increase the surface area, particularly when the applied profile may comprise corrugations, dimples, reticulations, waves or the like.
The applied profile may permit a desired predetermined increase in length and/or bore of the tube. The increase is achievable by application of a force smaller, usually much smaller, than that required to stretch the material appreciably beyond a predetermined limit.
These means allow the tube to accommodate changes in the bore of the host pipe and to deform to match the profile of bends and other fittings and broadly to follow the contours of the internal surface of the host pipe. This in turn allows the tube to be continuously adhered to the internal surface of the hostpipe, so that special provision to seal the annular gap is not required. It also allows the location off side connections to the pipe to be made visible, by pressurising the liner, thus facilitating their location.
An adhesive/sealant, hereinafter generally referred to as xe2x80x9cadhesivexe2x80x9d for brevity, or one component of a two part adhesive, may be applied to the internal surface of the host pipe prior to eversion of the liner into place, or the adhesive, or the second component of a two part adhesive may be applied to the surface of the liner as described below. For reasons given below, it is preferable for the adhesive or a component of the adhesive, to be applied to the surface of the liner.
The adhesive may comprise a layer of non-setting adhesive or a non-setting component of a 2-part adhesive to which the sheet material is bonded
The adhesive may comprise a material that does not require curing.
The adhesive component must be arranged to coat the internal surface of the liner prior to eversion. It would therefore be necessary to cover all the surfaces of the adhesive component that would otherwise be exposed, with a protective film, herein referred to as a release tape. The release tape is bonded only weakly to the adhesive. This allows for ease of storage, handling and use, by re-exposing the adhesive surface.
It is preferably a feature of the invention that the material should be inserted into the host pipe without being subjected to forces strong enough to cause the built in expansion capability of the material to be compromised. The principal means by which this is achieved is by arranging for most of the stress induced by the forces applied to overcome friction during the eversion process to be borne by a separate tape, filament or cable, loosely adhered to the liner along its entire length so as to distribute forces experienced by the liner evenly over its surface.
The release tape may be reinforced in a direction axially of the tube. This allows the finer to be pulled by the release tape through the pipe even against a significant resistance and without stretching the sheet material.
The material may be produced any material provided that it has the required properties to accept corrugation and to withstand the eversion process and may be formed into a tube. The material may be impervious to the fluid that the pipe is intended to convey, may be resistant to chemical attack from the said fluid and may be approved for use in contact with potable water.
The adhesive and the release tape may be applied to the exterior of the tube and the tube may be everted so that the adhesive and release tape are on the inside of the tube. This provides for ease of installation of the liner in a pipe.
The tube may be folded whereby its greatest lateral dimension is less than the diameter of the tube. This again provides for ease of insertion and use.
The tube may be formed to a cruciform shape and then flattened. This again provides for ease of installation and use.
A major component of the adhesive may comprise a butyl rubber. The adhesive may provide adhesion to a contaminated or rusty surface.
According to a second aspect of the invention there is provided apparatus for lining a pipe with a liner which is tubular, comprising means to draw the tube through the pipe, evert the tube and secure it to the pipe.
According to a third aspect of the invention there is provided apparatus for puncturing a liner in a pipe. This may comprise means to hold the punctured liner in position over a hole in the host pipe while providing relatively unrestricted fluid flow.
This provides for puncturing the material at positions where fluid is required to be allowed to flow from the pipe, for example at a branch pipe or junction. These are easily identified visually due to the flexible nature of the liner. There may be means to protect exposed surfaces of a layer of adhesive from contact with fluid in the pipe.
The apparatus may preferably be insertable into a hole in the pipe from interiorly thereof, preferably by being insertable by remote control from an exposed end of a lined part of a pipe.
According to a fourth aspect of the invention there is provided a pipe lined with a liner, as hereinbefore defined.
There may be a pipe junction which may have a fluid take-off through the liner at the junction.
A liner for a pipe and method of inserting it are hereinafter described, by way of example, with reference to the accompanying drawings.